1. Field of the Invention
The present invention relates to an airbag apparatus mountable on a vehicle and, more particularly, to an airbag apparatus including a pyrotechnic inflator that generates gas for inflating an airbag by chemical reaction.
2. Description of Related Art
A conventional airbag apparatus is known from Japanese Utility Model Registration No. 3,049,669 or U.S. Pat. No. 5,836,608 corresponding thereto. The airbag apparatus includes an inflatable airbag provided with a gas inlet, an inflator for supplying the airbag with inflation gas, a case for housing the airbag and inflator, and an annular retainer for holding down a periphery of the gas inlet port of the airbag for attaching the airbag to the case. When an airbag apparatus employs a pyrotechnic inflator that generates inflation gas by chemical reaction, the gas exited the inflator may contain hot residual particles that can damage the airbag if not removed or cooled off before reaching the airbag. To solve this problem, the above-mentioned airbag apparatus includes on the retainer a guide wall that deflects inflation gas exited the inflator away from the periphery of the gas inlet port of the airbag.
Another conventional airbag apparatus is known in JP 2004-001636A. This apparatus is provided on the retainer with a catch wall for catching such residual particles. The catch wall is tubular in shape and disposed around gas discharge ports of the inflator. The catch wall includes orifices for releasing inflation gas radially outwardly and catches residual particles by peripheral areas of the orifices when the gas passes through the orifices.
However, in the airbag apparatus disclosed in the former reference, the guide wall is simply oriented outwardly in order to deflect inflation gas away from the peripheral area of the gas inlet port of the airbag. This configuration still may deliver hot residual particles to a portion of the airbag that remains folded proximate the inflator, if not the peripheral area of the gas inlet port, in the initial stage of airbag inflation.
Moreover, in the airbag apparatus disclosed in the latter reference, the catch wall is a single tubular wall surrounding the gas discharge ports. With this configuration, if the inflator includes numerous gas discharge ports, the gas successively discharged from the discharge ports may hit the particles once caught by the catch wall and blow them off toward the airbag. These particles may damage the airbag if not have been cooled off enough by the catch wall. A reinforcing element that has been applied to a conventional airbag in order to cope with this problem has complicated the manufacturing process and increased manufacturing cost.
In another aspect, such configuration as to get rid of or lessen a heavy filter from the inflator in the light of weight reduction is likely to increase hot residual particles in inflation gas discharged from gas discharge ports of the inflator.